1. Field of the Invention
The invention relates to a filter comprising at least two inputs for receiving at least two signals, and an output for supplying an output signal.
The invention further relates to a signal processing device comprising such a filter.
The invention further relates to a teleconferencing system, a voice-controlled electronic device, and a noise cancellation system.
The invention further relates to a method for filtering at least two signals and for supplying an output signal.
Recent developments in audio and video systems require the use of multiple channel processing and reproduction with acoustic echo cancellers (AEC) and noise cancellers. For example in mini-group video conferencing systems, multiple channel transmission leads to a better “localization” of the diverse people in the room. This enhances the intelligibility and naturalness of the speech.
Further, multiple channel echo cancellation is needed in voice-controlled stereo audio and video equipment, such as television receivers, radio receivers, CD players, etc.
A multiple channel AEC can, in general, not be created by a simple combination of multiple single channel AEC's.
2. Description of the Related Art
U.S. Pat. No. 5,828,756 discloses a stereophonic communication system, such as a teleconferencing system, which involves selectively reducing the correlation between the individual channel signals of the stereophonic system. Herein, non-linearities are added to the input signals to reduce the correlation. However by adding these non-linearities, audible artifacts in the output signals are introduced. These non-linearities can (sometimes) be accepted in teleconferencing systems but are certainly not acceptable in other applications, such as supplying music, etc.